Skin And Muscle

Question 1

Epidermis

Answer 1

Stratified squamous epithelium with a basement membrane that connects it to dermis

It is avascular and has many layers

Question 2

Stratum basale

Answer 2

Deepest single layer of cells attached to dermis

Contains many stem cells to produce keratinocytes

Has a large nuclei and organelles

Site of Merkel cells and melanocytes

Question 3

Stratum spinosum

Answer 3

Has tonofilaments to resist tension, Langerhan cells and 8-10 layers of keratinocytes

Has large nucleus and organelles

Keratin filaments are linked to desmosomes

Question 4

Stratum granulosum

Answer 4

Has 3-5 layers of flattened keratinocytes undergoing apoptosis and lamellar granules that secrete lipids

Transition area between metabolically active and inactive cells of epidermis

Question 5

Stratum corneum

Answer 5

5 - 50 layers of stratified squamous epithelium with dead keratinocytes

Cells don’t have nucleus or organelles, form strong connections and are continuously shed

Can form calluses

Question 6

Stratum lucidum

Answer 6

4-6 layers of flattened dead keratinized cells that are only present in thick skin areas

Has a high conc of keratin and thick plasma membranes

Question 7

Dermis

Answer 7

Dense irregular connective tissue that has fibers that stretch and recoil and rich supply of nerves and blood vessels

Thicker than epidermis and is made up of the papillary and reticular regions

Question 8

Papillary region

Answer 8

Areolar connective tissue that has capillary loops and nerve endings

Question 9

Reticular region

Answer 9

Strong and elastic bundles of thick fibers, fibroblasts and macrophages

Have collagen, sebaceous (secrete sebum/oil) and sudoriferous (secrete sweat) glands

Question 10

Hypodermis

Answer 10

Sheet of connective areolar tissue and adipose cells which stores fat and anchors skin

Question 11

Keratinocytes

Answer 11

Produce keratin and lamellar granules

90% of epidermal cells

Question 12

Melanocytes

Answer 12

Produce melanin to protect from UV rays

Question 13

Langerhans cells

Answer 13

Macrophage - like dendritic cells that participate in immune response

Question 14

Merkel cells

Answer 14

Mechano-receptors associated with sensory nerve endings

Least % of epidermal cells

Question 15

Skeletal muscle fiber

Answer 15

Multi-nucleated

Sarcolemma transmits action potentials and opens to t-tubule system

Sarcoplasmic reticulum is linked to t-tubule system and releases Ca2+ to stimulate contraction

Question 16

Myofibrils

Answer 16

Bundles of contractile and elastic proteins comprised of sarcomeres

Question 17

Skeletal sarcomeres

Answer 17

Unit of contraction made up of overlapping thick and thin filaments which give a striated appearance

Question 18

Types of skeletal muscle fibers

Answer 18

Type I: slow speed and long duration of contraction, fatigue resistance, used in posture

Type IIa: intermediate speed and short duration of contraction, fatigue resistant, used in standing and walking

Type IIb: fast speed and short duration of contraction, easily fatigued and used in jumping

Question 19

Smooth muscle cells

Answer 19

Smaller than skeletal and is not striated since it doesn’t have sarcomeres, it is uninucleated and involuntary

Can be arranged as multi-unit or single-unit

Question 20

Multi-unit smooth muscle

Answer 20

Individual contraction for fine control

Question 21

Single - unit smooth muscle

Answer 21

Cells connected by gap junctions so the stimulus makes the whole sheet contract

Question 22

Cardiac muscle cells

Answer 22

Striated, uninucleated, involuntary, shorter than skeletal

1% of them are non-contractile known as pacemaker cells

Question 23

Pacemaker cells

Answer 23

Found in SAN and AVN, have a weak contraction and they control the rate of contractile cells